AC power line impedance monitoring method and system

Patent 7164275 Issued on January 16, 2007. Estimated Expiration Date:

September 30, 2024. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3904859

Ground fault circuit interrupter utilizing a single transformer
Patent #: 4001646
Issued on: 01/04/1977
Inventor: Howell

Ground fault circuit interrupter utilizing a single transformer
Patent #: 4150411
Issued on: 04/17/1979
Inventor: Howell

Method and apparatus for nondisruptively measuring line impedance at frequencies which are relatively close to the line frequency
Patent #: 5587662
Issued on: 12/24/1996
Inventor: Kelley, et al.

Impedance measurement in a high-voltage power system Patent #: 5631569
Issued on: 05/20/1997
Inventor: Moore, et al.

Inventor

Gasperi, Michael Lee

Application

No. 10955407 filed on 09/30/2004

US Classes:

324/652, Of a resonant circuit324/691, Using resistance or conductance measurement702/65, Including related electrical parameter361/45, With differential sensing in a single phase system324/713, With voltage or current signal evaluation361/42, Ground fault protection324/601, Calibration324/117R, Magnetic saturation (e.g., in field or in amplifier)324/663Where a material or object forms part of the dielectric being measured

Examiners

Primary: Hirshfeld, Andrew H.
Assistant: Teresinski, John

Attorney, Agent or Firm

Foreign Patent References

1237218 DE 03/01/1967
1257960 DE 01/01/1968
3600770 DE 11/01/1986
19504271 DE 02/01/1996
2498762 FR 07/01/1982

International Classes

G01R 27/28
G01R 27/08

Abstract

A technique for determining inductive and resistive components of power line impedance. A measurement circuit switches a burden or drain resistor between power line conductors to cause a droop or sag in a voltage waveform. The voltage waveform is sampled prior to inclusion of the resistor in the circuit, as well as after to identify the droop. The short circuit between the power lines is then removed by opening the circuit and a capacitor in the test circuitry causes a resonant ring due to the inductive component of the power line impedance. Based upon the period or frequency of the resonant ring, and upon the voltage measurements with and without the resistor in the circuit, the inductive and resistive components of power line impedance can be computed.

Other References

Operator's Manual ZM-100 Mains Impedance Meter; Precision Control Systems; Sold and Marketed by PowerLines; 41 pages.
Z-Brick features and specifications; Z-Brick, the newly introduced line-to-line impedance test otion for the EPA 2000; http://www.rxms.com/zbrick.htm; 2 pages.
Stephen B. Dubina, Jr. and Thomas D. Barkand; AC System Impedance Testing; Mine Safety and Health Administration Mine Electrical Systems Division; 8 pages.
SureTest Circuit Analyzer and SureTest w/AFCI Instructions; #61-154, #61-155, Ideal Industries, Inc.; 10 pages.
Adly A. Girgis and R. Brent McManis; Frequency Domain Techniques for Modeling Distribution or Transmission Networks Using Capacitor Switching Induced Transients, IEEE Transactions on Power Delivery, vol. 4, No. 3, Jul. 1989; 9 pages.
Keiju Matsui, Nobuyuki Ishigure, and Fukashi Ueda; On-line Impedance Meter to Measure the Impedance of a Distribution Line Using Inverter, IECON'01: The 27th Annual Conference of the IEEE Industrial Electronics Society; 2001: 7 pages.